This chapter provides a foundational understanding of food systems, exploring their key elements and the factors that shape system transformations. We delve into the interconnectedness of production, processing, distribution, and consumption, highlighting how these activities influence food availability, accessibility, and quality. The chapter summarizes the role of structural transformation in shaping how food systems are organized and operate. We discuss the challenges and opportunities associated with these transformations, particularly, in relation to the availability and affordability of nutritious and perishable foods that are essential for healthy diets. By understanding the complexities of food systems transformations, we can better comprehend and address the complex issues of food loss and waste that will be explored throughout this book.